1. Summary of the Invention
In accordance with the present invention, there are provided fully human contiguous heavy and light chain sequences spanning the complementarity determining regions monoclonal antibodies against human epidermal growth factor receptor (EGF-r). Nucleotide sequences encoding and amino acid sequences comprising heavy and light chain immunoglobulin molecules, particularly sequences corresponding to (CDR's), specifically from CDR1 through CDR3, are provided. Hybridomas expressing such immunoglobulin molecules and monoclonal antibodies are also provided. Also provided in accordance with the invention are antibodies that possess one or more of the following functional characteristics: (i) inhibit tyrosine phosphorylation of EGF-r, (ii) do not inhibit EGF-r internalization, (ii) inhibit EGF-r degradation, (iii) inhibition of EGF induced EGF-r degradation, (iv) protect threonine phosphorylation of EGF-r, (v) protect threonine phosphorylation of other molecules, particularly a 62 KD molecule identified by immunoprecipitation, and (vi) inhibit vascular endothelial cell growth factor signal by tumor cells by greater than 50% and endothelial cells by greater than 40% relative to control.
2. Background of the Technology
Most applications of monoclonal antibodies (MAbs) in cancer therapy rely on the ability of the antibody to specifically deliver to the cancerous tissues cytotoxic effector functions such as immune-enhancing isotypes, toxins or drugs. An alternative approach is to utilize MAbs to directly affect the survival of tumor cells by depriving them of essential extracellular proliferation signals, such as those mediated by growth factors through their cell receptors. One of the attractive targets in this approach is the epidermal growth factor receptor (EGFr), which binds EGF and transforming growth factor α (TGFα) (1-4). Binding of EGF or TGFα to EGFr, a 170 kDa transmembrane ell surface glycoprotein, triggers a cascade of cellular biochemical events, including EGFr autophosphorylation and internalization, which culminates in cell proliferation (1).
Several observations implicate EGFr in supporting development and progression of human solid tumors. Overexpression of EGFr has been shown to induce transformed properties in recipient cells (5). EGFr expression has been found to be up-regulated on many human tumors, including lung, colon, breast, prostate, brain, head and neck, ovarian and renal carcinoma, and the increase in receptor levels has been reported to be associated with a poor clinical prognosis (2, 3, 6-8). In many cases, the increased surface EGFr expression was accompanied by production of TGFα or EGF by the tumor cells, suggesting the involvement of an autocrine growth control in the progression of these tumors (2, 3, 6, 8). These observations suggested that blocking the interaction between the growth factors and EGFr could result in arrest of tumor growth and possibly affect tumor survival (2-4,6).
MAbs specific to the human EGFr, capable of neutralizing EGF and TGFα binding to tumor cells and of inhibiting ligand-mediated cell proliferation in vitro, have been generated from mice and rats (2,3,4,6). Some of these antibodies, such as the mouse 108 (9) 225 and 528 (2,3) or the rat ICR16, ICR62 and ICR64 (6,10, 11) MAbs, were evaluated extensively for their ability to affect tumor growth in xenograft mouse models. Most of the anti-EGFr MAbs were efficacious in preventing tumor formation in athymic mice when administered together with the human tumor cells (2,11). When injected into mice bearing established human tumor xenografts, the mouse MAbs 225 and 528 caused partial tumor regression and required the co-administration of chemotherapeutic agents, such as doxorubicin or cisplatin, for eradication of the tumors (2,3,12,13). A chimeric version of the 225 MAb (C225), in which the mouse antibody variable regions are linked to human constant regions, exhibited an improved in vivo anti-tumor activity but only at high doses (14, 15). The rat ICR16, ICR62, and ICR64 antibodies caused regression of established tumors but not their complete eradication (11). These results established EGFr as a promising target for antibody therapy against EGFr-expressing solid tumors and led to human clinical trials with the C225 MAb in multiple human solid cancers (2,3,6). However, the limited efficacy of these MAbs as monotherapeutic agents required their assessment in combination with chemotherapy (16, 17). This requirement can limit the utilization of anti-EGFr antibodies in patients for whom chemotherapy is not available. Therefore, the identification of an anti-EGFr antibody capable of eradicating established human tumors by itself can expand the patient populations and cancer indications to which EGFr antibody therapy can be applied successfully. In addition, the MAbs currently pursued in human clinical trials, being murine chimeric antibodies (2,4), are likely to induce immunogenic or allergic responses to the mouse components in immunocompetent patients, leading to reduction in the antibody efficacy and safety. Therefore, anti-EGFr antibody therapy can be fully evaluated with the availability of a fully human anti-EGFr antibody that exhibits therapeutic efficacy on EGFr-expressing tumors and that can be administered repeatedly to all appropriate patient populations.
EGF-r has been demonstrated to be overexpressed on many types of human solid tumors. Mendelsohn Cancer Cells 7:359 (1989), Mendelsohn Cancer Biology 1:339-344 (1990), Modjtahedi and Dean Int'l J. Oncology 4:277-296 (1994). For example, EGF-r overexpression has been observed in certain lung, breast, colon, gastric, brain, bladder, head and neck, ovarian, and prostate carcinomas. Modjtahedi and Dean Int'l J. Oncology 4:277-296 (1994). Both epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-α) have been demonstrated to bind to EGF-r and to lead to cellular proliferation and tumor growth.
Thus, certain groups have proposed that antibodies against EGF, TGF-α, and EGF-r may be useful in the therapy of tumors expressing or overexpressing EGF-r. Mendelsohn Cancer Cells 7:359 (1989), Mendelsohn Cancer Biology 1:339-344 (1990), Modjtahedi and Dean Int'l J. Oncology 4:277-296 (1994), Tosi et al. Intl J. Cancer 62:643-650 (1995). Indeed, it has been demonstrated that anti-EGF-r antibodies while blocking EGF and TGF-α binding to the receptor appear to inhibit tumor cell proliferation. At the same time, however, anti-EGF-r antibodies have not appeared to inhibit EGF and TGF-α independent cell growth. Modjtahedi and Dean Int'l J. Oncology 4:277-296 (1994).
In view of these findings, a number of murine and rat monoclonal antibodies against EGF-r have been developed and tested for their ability inhibit the growth of tumor cells in vitro and in vivo. Modjtahedi and Dean Int'l Oncology 4:277-296 (1994). The antibody that has apparently advanced the farthest in the clinic is a chimeric antibody, designated C225, which has a murine variable region and a human IgG1 constant region. Modjtahedi and Dean Int'l Oncology 4:277-296 (1994). The murine antibody, designated 225, upon which the C225 antibody is based, was developed by University of California and Rorer. See U.S. Pat. No. 4,943,533 and European Patent No. 359,282, the disclosures of which are hereby incorporated by reference. The C225 antibody was demonstrated to inhibit EGF-mediated tumor cell growth in vitro and inhibit human tumor formation in vivo in nude mice. The antibody, moreover, appeared to act in synergy with certain chemotherapeutic agents to eradicate human tumors in vivo in xenograft mouse models. Modjtahedi and Dean Int'l J. Oncology 4:277-296 (1994).
ImClone has been conducting human clinical trials using the anti-EGF-r antibody designated C225. Phase I and Phase I/II clinical trials in patients with head and neck, prostate, and lung carcinomas apparently have been, or are currently being, conducted with C225. In Phase I clinical trials, no toxicity was detected with multiple injections and with doses of up to perhaps 400 mg/m2, even in cases involving immuno compromised patients. Such studies were conducted as dose escalation studies comprising 5 doses of from about 5 to about 200 mg/m2 and were performed in combination with chemotherapy (i.e., doxorubicin, adriamycin, taxol, and cisplatin). In addition to the apparent safety data that has been generated in these studies, preliminary results from the studies appear to indicate some evidence of tumor shrinkage in 80% of patients having prostate cancer.
Each of these above-mentioned antibodies, however, possess murine or rat variable and/or constant regions. The presence of such murine or rat derived proteins can lead to the rapid clearance of the antibodies or can lead to the generation of an immune response against the antibody by a patient. In order to avoid the utilization of murine or rat derived antibodies, it has been postulated that one could introduce human antibody function into a rodent so that the rodent would produce fully human antibodies.
The ability to clone and reconstruct megabase-sized human loci in YACs and to introduce them into the mouse germline provides a powerful approach to elucidating the functional components of very large or crudely mapped loci as well as generating useful models of human disease. Furthermore, the utilization of such technology for substitution of mouse loci with their human equivalents could provide unique insights into the expression and regulation of human gene products during development, their communication with other systems, and their involvement in disease induction and progression.
An important practical application of such a strategy is the “humanization” of the mouse humoral immune system. Introduction of human immunoglobulin (Ig) loci into mice in which the endogenous Ig genes have been inactivated offers the opportunity to study the mechanisms underlying programmed expression and assembly of antibodies as well as their role in B-cell development. Furthermore, such a strategy could provide an ideal source for production of fully human monoclonal antibodies (Mabs)—an important milestone towards fulfilling the promise of antibody therapy in human disease. Fully human antibodies are expected to minimize the immunogenic and allergic responses intrinsic to mouse or mouse-derivatized Mabs and thus to increase the efficacy and safety of the administered antibodies. The use of fully human antibodies can be expected to provide a substantial advantage in the treatment of chronic and recurring human diseases, such as inflammation, autoimmunity, and cancer, which require repeated antibody administrations.
One approach towards this goal was to engineer mouse strains deficient in mouse antibody production with large fragments of the human Ig loci in anticipation that such mice would produce a large repertoire of human antibodies in the absence of mouse antibodies. Large human Ig fragments would preserve the large variable gene diversity as well as the proper regulation of antibody production and expression. By exploiting the mouse machinery for antibody diversification and selection and the lack of immunological tolerance to human proteins, the reproduced human antibody repertoire in these mouse strains should yield high affinity antibodies against any antigen of interest, including human antigens. Using the hybridoma technology, antigen-specific human Mabs with the desired specificity could be readily produced and selected.
This general strategy was demonstrated in connection with our generation of the first XenoMouse™ strains as published in 1994. See Green et al. Nature Genetics 7:13-21 (1994). The XenoMouse™ strains were engineered with yeast artificial chromosomes (YACs) containing 245 kb and 190 kb-sized germline configuration fragments of the human heavy chain locus and kappa light chain locus, respectively, which contained core variable and constant region sequences. Id. The human Ig containing YACs proved to be compatible with the mouse system for both rearrangement and expression of antibodies and were capable of substituting for the inactivated mouse Ig genes. This was demonstrated by their ability to induce B-cell development, to produce an adult-like human repertoire of fully human antibodies, and to generate antigen-specific human Mabs. These results also suggested that introduction of larger portions of the human Ig loci containing greater numbers of V genes, additional regulatory elements, and human Ig constant regions might recapitulate substantially the full repertoire that is characteristic of the human humoral response to infection and immunization. The work of Green et al. was recently extended to the introduction of greater than approximately 80% of the human antibody repertoire through introduction of megabase sized, germline configuration YAC fragments of the human heavy chain loci and kappa light chain loci, respectively. See Mendez et al. Nature Genetics 15:146-156 (1997) and U.S. patent application Ser. No. 08/759,620, filed Dec. 3, 1996, the disclosures of which are hereby incorporated by reference.
Such approach is further discussed and delineated in U.S. patent application Ser. No. 07/466,008, filed Jan. 12, 1990, Ser. No. 07/610,515, filed Nov. 8, 1990, Ser. No. 07/919,297, filed Jul. 24, 1992, Ser. No. 07/922,649, filed Jul. 30, 1992, filed Ser. No. 08/031,801, filed Mar. 15, 1993, Ser. No. 08/112,848, filed Aug. 27, 1993, Ser. No. 08/234,145, filed Apr. 28, 1994, Ser. No. 08/376,279, filed Jan. 20, 1995, Ser. No. 08/430,938, Apr. 27, 1995, Ser. No. 08/464,584, filed Jun. 5, 1995, Ser. No. 08/464,582, filed Jun. 5, 1995, Ser. No. 08/463,191, filed Jun. 5, 1995, Ser. No. 08/462,837, filed Jun. 5, 1995, Ser. No. 08/486,853, filed Jun. 5, 1995, Ser. No. 08/486,857, filed Jun. 5, 1995, Ser. No. 08/486,859, filed Jun. 5, 1995, Ser. No. 08/462,513, filed Jun. 5, 1995, Ser. No. 08/724,752, filed Oct. 2, 1996, and Ser. No. 08/759,620, filed Dec. 3, 1996. See also Mendez et al. Nature Genetics 15:146-156 (1997). See also European Patent No., EP 0 463 151 B1, grant published Jun. 12, 1996, International Patent Application No., WO 94/02602, published Feb. 3, 1994, International Patent Application No., WO 96/34096, published Oct. 31, 1996, and PCT Application No. PCT/US96/05928, filed Apr. 29, 1996. The disclosures of each of the above-cited patents, applications, and references are hereby incorporated by reference in their entirety.
In an alternative approach, others, including GenPharm International, Inc., have utilized a “minilocus” approach. In the minilocus approach, an exogenous Ig locus is mimicked through the inclusion of pieces (individual genes) from the Ig locus. Thus, one or more VH genes, one or more DH genes, one or more JH genes, a mu constant region, and a second constant region (preferably a gamma constant region) are formed into a construct for insertion into an animal. This approach is described in U.S. Pat. No. 5,545,807 to Surani et al. and U.S. Pat. Nos. 5,545,806 and 5,625,825, both to Lonberg and Kay, and GenPharm International U.S. patent application Ser. No. 07/574,748, filed Aug. 29, 1990, Ser. No. 07/575,962, filed Aug. 31, 1990, Ser. No. 07/810,279, filed Dec. 17, 1991, Ser. No. 07/853,408, filed Mar. 18, 1992, Ser. No. 07/904,068, filed Jun. 23, 1992, Ser. No. 07/990,860, filed Dec. 16, 1992, Ser. No. 08/053,131, filed Apr. 26, 1993, Ser. No. 08/096,762, filed Jul. 22, 1993, Ser. No. 08/155,301, filed Nov. 18, 1993, Ser. No. 08/161,739, filed Dec. 3, 1993, Ser. No. 08/165,699, filed Dec. 10, 1993, Ser. No. 08/209,741, filed Mar. 9, 1994, the disclosures of which are hereby incorporated by reference. See also International Patent Application Nos. WO 94/25585, published Nov. 10, 1994, WO 93/12227, published Jun. 24, 1993, WO 92/22645, published Dec. 23, 1992, WO 92/03918, published Mar. 19, 1992, the disclosures of which are hereby incorporated by reference in their entirety. See further Taylor et al., 1992, Chen et al., 1993, Tuaillon et al., 1993, Choi et al., 1993, Lonberg et al., (1994), Taylor et al., (1994), and Tuaillon et al., (1995), the disclosures of which are hereby incorporated by reference in their entirety.
The inventors of Surani et al., cited above and assigned to the Medical Research Counsel (the “MRC”), produced a transgenic mouse possessing an Ig locus through use of the minilocus approach. The inventors on the GenPharm International work, cited above, Lonberg and Kay, following the lead of the present inventors, proposed inactivation of the endogenous mouse Ig locus coupled with substantial duplication of the Surani et al. work.
An advantage of the minilocus approach is the rapidity with which constructs including portions of the Ig locus can be generated and introduced into animals. Commensurately, however, a significant disadvantage of the minilocus approach is that, in theory, insufficient diversity is introduced through the inclusion of small numbers of V, D, and J genes. Indeed, the published work appears to support this concern. B-cell development and antibody production of animals produced through use of the minilocus approach appear stunted. Therefore, research surrounding the present invention has consistently been directed towards the introduction of large portions of the Ig locus in order to achieve greater diversity and in an effort to reconstitute the immune repertoire of the animals.
Human anti-mouse antibody (HAMA) responses have led the industry to prepare chimeric or otherwise humanized antibodies. While the C225 antibody is a chimeric antibody, having a human constant region and a murine variable region, it is expected that certain human anti-chimeric antibody (HACA) responses will be observed, particularly in chronic or multi-dose utilizations of the antibody.
Thus, it would be desirable to provide fully human antibodies against EGF-r that possess similar or enhanced activities as compared to C225 in order to vitiate concerns and/or effects of HAMA or HACA response.